The air quality in the East San Gabriel Valley, Riverside County and the communities within the San Bernardino Mountains will be unhealthy for sensitive people on Thursday, according to the South Coast Air Quality Management District.

People who are most sensitive to lung-damaging air pollution should limit outdoor exercising and avoid any type of heavy exertion, according to the smog district.

These include: athletes, children and teenagers, older adults and people with asthma, lung disease and heart ailments who are more prone to a breathing problem caused by the caustic emissions in the air and the length of exposure, said Patrick Chandler, SCAQMD spokesman.

A health advisory was issued from the Los Angeles County Department of Public Health for Thursday encompassing a wide swath of the San Gabriel Valley, including the cities of Temple City, Arcadia, Sierra Madre, Monrovia, Duarte, El Monte, Baldwin Park, Covina, West Covina, Azusa and Glendora.

San Bernardino County cities with the forecast are Bloomington, Colton, Fontana, Grand Terrace, Highland, Loma Linda, Mentone, Redlands, Rialto, San Bernardino and Yucaipa, as well as San Bernardino Mountain communities including Big Bear, Crestline, and Lake Arrowhead.

Dr. Jeffrey Gunzenhauser, the county’s interim health officer, advises people in these regions of Southern California with heart or lung conditions to “minimize outdoor activities.”

“Children, older adults, people with asthma, the elderly and those with heart disease we are advising them to avoid sports, running or even walking outdoors,” Chandler said. “They could have an asthma attack.”

Smoke from fires

Smoke can be seen for miles from a brush fire along Laguna Canyon Road near Lake Forest Drive.on Wednesday, June 6, 2018. (Photo courtesy of Jordan Villwock)

Fires in Benedict Canyon, Chino, Santa Clarita, Chatsworth, Thousand Oaks and Laguna Beach produced heavy smoke containing a particular kind of air pollution that can lodge in the lungs and even the brain, according to the SCAQMD and the U.S. Environmental Protection Agency.

The SCAQMD forecast relies mostly on elevated levels of ozone, a gas created by a chemical reaction with oxides of nitrogen, volatile organic compounds in the presence of sunlight. The source of those emissions are motor vehicles, chemical solvents, industrial emissions, vapors and some natural sources.

Good air near beaches

Air quality in north and central Orange County will be moderate Thursday. South Orange County and the beach communities in Los Angeles County will have good air quality.

The categories, known as the Air Quality Index are as follows (from cleanest to dirtiest): good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous.

Steve Scauzillo covers environment and transportation for the Southern California News Group. He has won two journalist of the year awards from the Angeles Chapter of the Sierra Club and is a recipient of the Aldo Leopold Award for Distinguished Editorial Writing on environmental issues. Steve studied biology/chemistry when attending East Meadow High School and Nassau College in New York (he actually loved botany!) and then majored in social ecology at UCI until switching to journalism. He also earned a master's degree in media from Cal State Fullerton. He has been an adjunct professor since 2005. Steve likes to take the train, subway and bicycle – sometimes all three – to assignments and the newsroom. He is married to Karen E. Klein, a former journalist with Los Angeles Daily News, L.A. Times, Bloomberg and the San Fernando Valley Business Journal and now vice president of content management for a bank. They have two grown sons, Andy and Matthew. They live in Pasadena. Steve recently watched all of “Star Trek” the remastered original season one on Amazon, so he has an inner nerd.